Support for reading (and writing) of single file yaml files

[michal-szostak]

@GraemeWatt asked me about possibility of supporting single file yaml submission (http://hepdata.cedar.ac.uk/view/ins1203852/yaml). If this is also a standard, I think it should be supported (both for reading and writing). I'm putting an issue here in order to allow some discussion and tracking of the progress. Any comments on this one @eamonnmag ?

[eamonnmag]

At the minute, I split the files up and then load them. The reason for this is that we need to do this anyway so that users have the option to download a selection of the data tables as opposed to everything. Additionally, by having records split up, the load and rendering speeds for displaying individual records is smaller.

We can support upload of single files by hooking some of the code I've created for the migrator in to the loader to split the files, and then load. This would not be a problem.

[GraemeWatt]

I just tried the --single-file option to convert sample.input to YAML output with version 0.1.16. The output YAML format is different from http://hepdata.cedar.ac.uk/view/ins1203852/yaml , i.e. two YAML documents (instead of just one) are written for every table: could this please be fixed?

Also, it would be nice to add the --single-file option for an input YAML file (at the moment it is only available for an output YAML file).

[michal-szostak]

I know that for now it's only available for output. I was going to add this functionality to yaml parser after finishing ROOT output. As for bug I'll check it out because I thought that I had that code well covered in tests.